The U.S. Supreme Court issued a ruling in the case of Environmental Protection Agency et al. v. EME Homer City Generation, L.P., et al and American Lung Association et al., v. EME Homer City Generation, L.P., et al. The cases focuses on efforts of Congress and EPA to address the problem of air pollution emitted in one state, which has caused harm in other states. As part of the Clean Air Act (CAA), Congress included a Good Neighbor Provision. This provision calls on States to prohibit in-state sources “from emitting any air pollutant which will…contribute significantly to downwind states ability to maintain any EPA national air quality standard.” The opinion stated:
In sum, we hold that the CAA does not command that States be given a second opportunity to file a SIP after EPA has quantified the State’s interstate pollution obligations. We further conclude that the Good Neighbor Provision does not require EPA to disregard costs and consider exclusively each upwind State’s physically proportionate responsibility for each downwind air quality problem. EPA’s cost-effective allocation of emission reductions among upwind States, we hold, is a permissible, work- able, and equitable interpretation of the Good Neighbor Provision.
The Supreme Court ruled 6-2 that EPA was not in violation of the CAA when it implemented its Cross-State Air Pollution Rule (CSAPR), determining that states in fact missed an opportunity to submit their own plans. The ruling overturns a decision from a D.C. Circuit court ruling in August 2012.